Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
vfs: expose delegation support to userland
Now that support for recallable directory delegations is available,
expose this functionality to userland with new F_SETDELEG and F_GETDELEG
commands for fcntl().
Note that this also allows userland to request a FL_DELEG type lease on
files too. Userland applications that do will get signalled when there
are metadata changes in addition to just data changes (which is a
limitation of FL_LEASE leases).
These commands accept a new "struct delegation" argument that contains a
flags field for future expansion.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://patch.msgid.link/20251111-dir-deleg-ro-v6-17-52f3feebb2f2@kernel.org
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
authored by
Jeff Layton
and committed by
Christian Brauner
1602bad1
8b99f6a8
+76
-5
+13
fs/fcntl.c
+13
fs/fcntl.c
···
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struct file *filp)
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{
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void __user *argp = (void __user *)arg;
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+
struct delegation deleg;
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int argi = (int)arg;
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struct flock flock;
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long err = -EINVAL;
···
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break;
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case F_SET_RW_HINT:
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err = fcntl_set_rw_hint(filp, arg);
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+
break;
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+
case F_GETDELEG:
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if (copy_from_user(&deleg, argp, sizeof(deleg)))
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return -EFAULT;
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+
err = fcntl_getdeleg(filp, &deleg);
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if (!err && copy_to_user(argp, &deleg, sizeof(deleg)))
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return -EFAULT;
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+
break;
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+
case F_SETDELEG:
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if (copy_from_user(&deleg, argp, sizeof(deleg)))
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return -EFAULT;
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err = fcntl_setdeleg(fd, filp, &deleg);
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break;
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default:
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break;
+40
-5
fs/locks.c
+40
-5
fs/locks.c
···
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* XXX: sfr & willy disagree over whether F_INPROGRESS
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* should be returned to userspace.
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*/
1706
-
int fcntl_getlease(struct file *filp)
1706
+
static int __fcntl_getlease(struct file *filp, unsigned int flavor)
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{
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struct file_lease *fl;
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struct inode *inode = file_inode(filp);
···
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list_for_each_entry(fl, &ctx->flc_lease, c.flc_list) {
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if (fl->c.flc_file != filp)
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continue;
1722
-
type = target_leasetype(fl);
1722
+
if (fl->c.flc_flags & flavor)
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type = target_leasetype(fl);
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break;
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}
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spin_unlock(&ctx->flc_lock);
···
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locks_dispose_list(&dispose);
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}
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return type;
1731
+
}
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+
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+
int fcntl_getlease(struct file *filp)
1734
+
{
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return __fcntl_getlease(filp, FL_LEASE);
1736
+
}
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+
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int fcntl_getdeleg(struct file *filp, struct delegation *deleg)
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+
{
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if (deleg->d_flags != 0 || deleg->__pad != 0)
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return -EINVAL;
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deleg->d_type = __fcntl_getlease(filp, FL_DELEG);
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return 0;
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}
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/**
···
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}
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EXPORT_SYMBOL_GPL(vfs_setlease);
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2041
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-
static int do_fcntl_add_lease(unsigned int fd, struct file *filp, int arg)
2042
+
static int do_fcntl_add_lease(unsigned int fd, struct file *filp, unsigned int flavor, int arg)
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{
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struct file_lease *fl;
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struct fasync_struct *new;
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int error;
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-
fl = lease_alloc(filp, FL_LEASE, arg);
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+
fl = lease_alloc(filp, flavor, arg);
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if (IS_ERR(fl))
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return PTR_ERR(fl);
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···
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if (arg == F_UNLCK)
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return vfs_setlease(filp, F_UNLCK, NULL, (void **)&filp);
2098
-
return do_fcntl_add_lease(fd, filp, arg);
2084
+
return do_fcntl_add_lease(fd, filp, FL_LEASE, arg);
2085
+
}
2086
+
2087
+
/**
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* fcntl_setdeleg - sets a delegation on an open file
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* @fd: open file descriptor
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* @filp: file pointer
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* @deleg: delegation request from userland
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*
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* Call this fcntl to establish a delegation on the file.
2094
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* Note that you also need to call %F_SETSIG to
2095
+
* receive a signal when the lease is broken.
2096
+
*/
2097
+
int fcntl_setdeleg(unsigned int fd, struct file *filp, struct delegation *deleg)
2098
+
{
2099
+
/* For now, no flags are supported */
2100
+
if (deleg->d_flags != 0 || deleg->__pad != 0)
2101
+
return -EINVAL;
2102
+
2103
+
if (deleg->d_type == F_UNLCK)
2104
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return vfs_setlease(filp, F_UNLCK, NULL, (void **)&filp);
2105
+
return do_fcntl_add_lease(fd, filp, FL_DELEG, deleg->d_type);
2099
2106
}
2100
2107
2101
2108
/**
+12
include/linux/filelock.h
+12
include/linux/filelock.h
···
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int fcntl_setlease(unsigned int fd, struct file *filp, int arg);
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int fcntl_getlease(struct file *filp);
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+
int fcntl_setdeleg(unsigned int fd, struct file *filp, struct delegation *deleg);
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+
int fcntl_getdeleg(struct file *filp, struct delegation *deleg);
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static inline bool lock_is_unlock(struct file_lock *fl)
164
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{
···
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static inline int fcntl_getlease(struct file *filp)
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{
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return F_UNLCK;
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+
}
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+
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+
static inline int fcntl_setdeleg(unsigned int fd, struct file *filp, struct delegation *deleg)
282
+
{
283
+
return -EINVAL;
284
+
}
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+
286
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static inline int fcntl_getdeleg(struct file *filp, struct delegation *deleg)
287
+
{
288
+
return -EINVAL;
281
289
}
282
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static inline bool lock_is_unlock(struct file_lock *fl)
+11
include/uapi/linux/fcntl.h
+11
include/uapi/linux/fcntl.h
···
79
79
*/
80
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#define RWF_WRITE_LIFE_NOT_SET RWH_WRITE_LIFE_NOT_SET
81
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+
/* Set/Get delegations */
83
+
#define F_GETDELEG (F_LINUX_SPECIFIC_BASE + 15)
84
+
#define F_SETDELEG (F_LINUX_SPECIFIC_BASE + 16)
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+
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/* Argument structure for F_GETDELEG and F_SETDELEG */
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+
struct delegation {
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uint32_t d_flags; /* Must be 0 */
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+
uint16_t d_type; /* F_RDLCK, F_WRLCK, F_UNLCK */
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+
uint16_t __pad; /* Must be 0 */
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+
};
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+
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/*
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* Types of directory notifications that may be requested.
84
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*/